Python：判断真假
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Python : While True or False
提问by Tolga Varol
I am not an experienced programmer, I have a problem with my code, I think it's a logical mistake of mine but I couldn't find an answer at http://anh.cs.luc.edu/python/hands-on/3.1/handsonHtml/whilestatements.html.
What I want is to check if the serial device is locked, and the different between conditions that "it is locked" and "it isn't locked" is that there are 4 commas ,,,,in the line which contains GPGGAletters. So I want my code to start if there isn't ,,,,but I guess my loop is wrong. Any suggestions will be appreciated. Thanks in advance.
我不是一个有经验的程序员，我的代码有问题，我认为这是我的逻辑错误，但我在http://anh.cs.luc.edu/python/hands-on/找不到答案3.1/handsonHtml/whilestatements.html。我想要的是检查串行设备是否被锁定，“它被锁定”和“它没有被锁定”的条件之间的区别是,,,,在包含GPGGA字母的行中有4个逗号。所以我希望我的代码在没有的情况下启动，,,,,但我想我的循环是错误的。任何建议将不胜感激。提前致谢。
import serial
import time
import subprocess
file = open("/home/pi/allofthedatacollected.csv", "w") #"w" will be "a" later
file.write('\n')
while True:
ser = serial.Serial("/dev/ttyUSB0", 4800, timeout =1)
checking = ser.readline();
if checking.find(",,,,"):
print "not locked yet"
True
else:
False
print "locked and loaded"
. . .
. . .
采纳答案by Martijn Pieters
Use breakto exit a loop:
使用break退出循环：
while True:
ser = serial.Serial("/dev/ttyUSB0", 4800, timeout =1)
checking = ser.readline();
if checking.find(",,,,"):
print "not locked yet"
else:
print "locked and loaded"
break
The Trueand Falseline didn't do anything in your code; they are just referencing the built-in boolean values without assigning them anywhere.
在True与False线没有做你的代码什么; 他们只是引用内置的布尔值，而没有在任何地方分配它们。
回答by Morten Jensen
You can use a variable as condition for your whileloop instead of just while True. That way you can change the condition.
您可以将变量用作while循环的条件，而不仅仅是while True. 这样你就可以改变条件。
So instead of having this code:
因此，不要使用此代码：
while True:
...
if ...:
True
else:
False
... try this:
... 尝试这个：
keepGoing = True
while keepGoing:
ser = serial.Serial("/dev/ttyUSB0", 4800, timeout =1)
checking = ser.readline();
if checking.find(",,,,"):
print "not locked yet"
keepGoing = True
else:
keepGoing = False
print "locked and loaded"
EDIT:
编辑：
Or as another answerer suggests, you can just breakout of the loop :)
或者正如另一位回答者所建议的那样，您可以break跳出循环:)
